FYCO1 mediates clearance of α‐synuclein aggregates through a Rab7‐dependent mechanism. Issue 4 (23rd July 2018)

• Record Type: Journal Article
• Authors: Saridaki, Theodora; Nippold, Markus; Dinter, Elisabeth; Roos, Andreas; Diederichs, Leonie; Fensky, Luisa; Schulz, Jörg B.; Falkenburger, Björn H.
• Is Part Of: Journal of neurochemistry. Volume 146:Issue 4(2018)
• Page Start: 474
• Page End: 492
• Publication Date: 2018-07-23
• Subjects: autophagy -- Parkinson's disease -- secretory autophagy -- spread of aggregates -- synuclein; Neurochemistry -- Periodicals; 616.8042
• DOI: 10.1111/jnc.14461
• Languages: English
• ISSNs: 0022-3042

Abstract

Abstract: Parkinson's disease can be caused by mutations in the α‐synuclein gene and is characterized by aggregates of α‐synuclein protein. We have previously shown that over‐expression of the small GTPase Rab7 can induce clearance of α‐synuclein aggregates. In this study, we investigate which Rab7 effectors mediate this effect. To model Parkinson's disease, we expressed the pathogenic A53T mutant of α‐synuclein in HEK293T cells and Drosophila melanogaster . We tested the Rab7 effectors FYVE and coiled‐coil domain‐containing protein 1 (FYCO1) and Rab‐interacting lysosomal protein (RILP). FYCO1‐EGFP‐decorated vesicles containing α‐synuclein. RILP‐EGFP also decorated vesicular structures, but they did not contain α‐synuclein. FYCO1 over‐expression reduced the number of cells with α‐synuclein aggregates, defined as visible particles of EGFP‐tagged α‐synuclein, whereas RILP did not. FYCO1 but not RILP reduced the amount of α‐synuclein protein as assayed by western blot, increased the disappearance of α‐synuclein aggregates in time‐lapse microscopy and decreased α‐synuclein‐induced toxicity assayed by the Trypan blue assay. siRNA‐mediated knockdown of FYCO1 but not RILP reduced Rab7‐induced aggregate clearance. Collectively, these findings indicate that FYCO1 and not RILP mediates Rab7‐induced aggregate clearance. The effect of FYCO1 on aggregate clearance was blocked by dominant negative Rab7 indicating that FYCO1 requires active Rab7 to function. Electron microscopic analysis and insertion of lysosomal membranes into the plasma membrane indicate that FYCO1 could lead to secretion of α‐synuclein aggregates. Extracellular α‐synuclein as assayed by ELISA was, however, not increased with FYCO1. Coexpression of FYCO1 in the fly model decreased α‐synuclein aggregates as shown by the filter trap assay and rescued the locomotor deficit resulting from neuronal A53T‐α‐synuclein expression. This latter finding confirms that a pathway involving Rab7 and FYCO1 stimulates degradation of α‐synuclein and could be beneficial in patients with Parkinson's disease. Open Science Badges: This article has received a badge for *Open Data* because it made the data publicly available. The data can be accessed athttps://osf.io/93n6m . The article has received the badge for *Open Material* as well, because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found athttps://cos.io/our-services/open-science-badges/ . Abstract : Parkinson's disease is characterized by aggregates of α‐synuclein. Cells can degrade these aggregates by transport towards the aggresome and autophagy. In order to develop therapies for Parkinson's disease, we investigate strategies that increase aggregate clearance. One such strategy is over‐expression of Rab7. In this work, we demonstrate that FYVE and coiled‐coil domain‐containing protein 1 (FYCO1), a Rab7 binding protein found on autophagosomes, recapitulates and mediates the effects of Rab7. For instance, FYCO1 induced disappearance of α‐synuclein aggregates in time‐lapse microscopy and decreased the α‐synuclein‐dependent locomotor deficit in a fly model. Mechanistically, FYCO1 promoted fusion of lysosomal compartments with the plasma membrane, indicating that FYCO1 might instigate secretion of α‐synuclein. Open Science: This manuscript was awarded with the Open Materials and Open Data Badge (https://osf.io/93n6m/ ) For more information see:https://cos.io/our-services/open-science-badges/